Other Comprehensive Income: Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	$ (27,346)	$ (30,655)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(20,084)	(27,346)
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(14,790)	(15,077)
Other comprehensive income (loss), before reclassifications	1,959	(1,062)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(11,176)	(14,790)
Accumulated Defined Benefit Plans Adjustment \| Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	1,655	1,349
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications	4,982	(1,109)
Accumulated Other Comprehensive Income (Loss) \| Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	2,280	4,418
Interest Rate Swap \| Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	(12,558)	(15,122)
Other comprehensive income (loss), before reclassifications	0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	(10,384)	(12,558)
Interest Rate Swap \| Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges \| Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	2,174	2,564
Commodity Contract \| Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period Start	2	(456)
Other comprehensive income (loss), before reclassifications	3,023	(47)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Period End	1,476	2
Commodity Contract \| Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges \| Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCI	$ (1,549)	$ 505